Adaptation of diet in a changed environment: increased consumption of the lobster krill Munida gregaria (Fabricius, 1793) by Argentine hake.

BELLEGGIA MAURO; GIBERTO DIEGO; BREMEC CLAUDIA

Marine Ecology

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2017 vol. 38 p. 1 - 9

The analysis described in this paper is based on a well-replicateddecadal-term (2005?2014) stomach content data set to infer inter-annualfluctuations in the diet of the Argentine hake Merluccius hubbsi, an opportunistic predator in San Jorge Gulf (SJG)ecosystem in the Southwest Atlantic. Ten research cruises were carried out eachyear during January from 2005 to 2014. A total of 18461 specimens of theArgentine hake M. hubbsi wereanalyzed, from which 6777 (36.71%) contained food in their stomachs. The dietof Argentine hake M. hubbsi wasmarkedly different since 2011, with much larger consumption of Munida gregaria. The frequency ofoccurrence (%F) of Munida gregaria inthe stomachs contents of Argentine hake increased since the year 2009, mostnoticeable since 2011, and mostly over the southern region of the SJG. The mainpredators of the lobster krill M.gregaria in the SJG are two species of teleost fish (Pink Cusk eel Genypterus blacodes, Argentine seabass Acanthistius brasilianus) and three Rajidaeskates (Zearaja chilensis, Psammobatis spp. and Sympterygia bonapartii), which exhibiteddecreased catches. The increased consumption of lobster krill M. gregaria by the Argentine hake M. hubbsi,  coupled with decreasedtrends in abundance of the main predators of the lobster krill during the lastdecade, argue for a top-down trophic dynamic control in the SJG ecosystem.